In recent years, flat panel-type display devices such as liquid crystal display devices have been commercialized and used in various electronic devices.
FIG. 19 is a perspective view illustrating a liquid crystal cell used in a liquid crystal display device. FIG. 18 is an enlarged perspective view showing, on an enlarged scale, a portion of FIG. 19.
A liquid crystal cell 100 has a structure in which a device substrate 102 and a counter substrate 101 are attached to each other with a liquid crystal layer (not shown), which is sealed by a sealing member (not shown), interposed therebetween. A row control circuit 103, a column control circuit 104, a group of wires 105, pixels, etc., are formed monolithically on the surface of the device substrate 102 that is closer to the liquid crystal layer. A light-blocking film (black matrix: often referred to as “BM”) 113, a color filter (not shown), etc., are formed on the surface of the counter substrate 101 that is closer to the liquid crystal layer. An FPC (flexible printed circuit board) 106 is attached to the so-called “terminal region” of the device substrate 102. An optical film 107 such as a polarizer or a phase plate is attached to the outer-side surface of the liquid crystal cell 100.
In the present specification, the substrate on which the light-blocking film 113 is formed (the counter substrate 101) is referred to as the first substrate 101, and the substrate (the device substrate 102) to be attached thereto is referred to as the second substrate 102.
In general, the outer-side surface of the first substrate 101 serves as the display surface, and a backlight 111 including a light source 108 such as a cold-cathode tube or an LED and a light guide member 109 is arranged on the back of the second substrate 102, thus forming a so-called “transmissive-type” liquid crystal display device 110.
The light-blocking film 113 is formed around the whole display region including gap regions between pixels and a group of pixels. The light-blocking film 113 blocks unnecessary light from the backlight 111 on the back side, thus realizing a desirable contrast and also serving as a so-called “break line member” for preserving the aesthetically pleasant appearance of the bezel of the display device.
The liquid crystal cell 100 described above is normally manufactured by being cut out from large mother glasses 115 and 116. FIG. 20 is a perspective view showing the step of cutting out the liquid crystal cell 100 from the mother glasses 115 and 116.
Generally, after the mother glass 115 of the first substrate 101 and the mother glass 116 of the second substrate 102 are attached to each other, the mother glasses 115 and 116 are cut along an outer shape of a predetermined size, which is to be the liquid crystal cell 100. The cutting is done by a so-called “scribe-break method”, for example. Specifically, as shown in FIG. 20, parallel grooves (scribe grooves) 118 are formed in advance on the surface of each of the mother glasses 115 and 116 using a rotary blade (scribing wheel) 117, after which an impact is applied. Thus, the glasses are cut into a plurality of liquid crystal cells 100.
The thickness of the first substrate 101 and that of the second substrate 102 are defined to be the same at about 0.5 mm, for example. While other terms such as “dividing”, “severing” or “separating” may be used instead of the term “cutting”, they are not substantially different in meaning but are merely different expressions used by different people in the art.
In such a cutting process, markings formed in advance on the mother glasses 115 and 116 may be used in some cases for alignment in a cutting process or for checking the finish of the cut position. As shown in FIG. 18, a marking may be formed on the surface of the first substrate 101 that is closer to the second substrate 102 (a marking A) or on the surface of the second substrate 102 that is closer to the first substrate 101 (a marking B). Moreover, the cut position of the first substrate 101 may be checked by a marking C formed on the second substrate 102.
The marking A on the first substrate 101 is formed by a light-blocking film of a metal or a black resin, and the marking B and the marking C on the second substrate 102 are formed by a thin metal film that forms a wire for an active matrix-type display device, for example.
A display device produced by cutting as described above normally employs a configuration where the light-blocking film is formed avoiding the outside area within a certain distance from the cut position, as disclosed in Patent Documents 1 and 2, for example.
Patent Document 1: Japanese Laid-Open Patent Publication No. H09-5731
Patent Document 2: Japanese Laid-Open Patent Publication No. H05-224196
Patent Document 3: Japanese Laid-Open Patent Publication No. 2004-46115